Based on the physical concept of heat energy of pre-ignition,a new fire susceptibility index (FSI) is used to estimate forest fire risk. This physical basis allows calculation of ignition probabilities and comparisons...Based on the physical concept of heat energy of pre-ignition,a new fire susceptibility index (FSI) is used to estimate forest fire risk. This physical basis allows calculation of ignition probabilities and comparisons of fire risk across eco-regions. The computation of the index requires inputs of fuel temperature and fuel moisture content (FMC),both of which can be estimated using remote sensing data. While ASTER data for land surface temperatures (LST) was used as proxys for fuel temperatures,fuel moisture content is estimated by regression technique utilizing the ratio NDVI/LST of ASTER data. FSIs are computed in peninsular Malaysia for nine days before the fires of 2004 and 2005 and validated with fire occurrence data. Results show that the FSI increases as the day approaches the fire day. This trend can be observed clearly about four days before the day of fire. It suggests that FSI can be a good estimator of fire risk. The physical basis provides a more meaningful FSI,allows calculation of ignition probabilities and facilitates the development of a future class of fire risk models. FSI can be used to compare fire risk across different eco-regions and time periods. FSI retains the flexibility to be localized to a vegetation type or eco-regions for improved performance.展开更多
To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is...To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is investigated through laboratory analyses and tests.The four debris-flow materials can all be remolded into coherent,homogeneous cylinders with high densification and strength–porosity of 25%-36%,mean pore-throat radius of 0.46-5.89μm,median pore-throat radius of 0.43-4.28μm,P-wave velocity of 800-1200 m/s,modulus of elasticity of 28-103 MPa,unconfined compressive strength(UCS)of 220-760 kPa,and cohesion of 65-281 kPa.Based on the comparison in slurryability and formability among debris-flow deposits,granular flow deposits,fluvial deposits,residual lateritic clay and loess,whether a sediment can be cast into competent cylinders for physico-mechanical tests can be regarded as a diagnostic evidence of old debris-flow deposits.The discrepancy in physico-mechanical properties among the four debris-flow deposits suggests that the combination of foregoing physico-mechanical parameters can characterize assembling characteristics of debris flow-related sediments including grain size distribution,mineralogy,and accidental detritus.Four deposited sediments above can be surprisingly classified as hard soil-soft rocks according to UCS,and the hard soil-soft rock behaviors can advance the further understanding of debris flows.展开更多
In this paper, an attempt to analyse landslide hazard and vulnerability in the municipality of Pahuatlfin, Puebla, Mexico, is presented. In order to estimate landslide hazard, the susceptibility, magnitude （area-velo...In this paper, an attempt to analyse landslide hazard and vulnerability in the municipality of Pahuatlfin, Puebla, Mexico, is presented. In order to estimate landslide hazard, the susceptibility, magnitude （area-velocity ratio） and landslide frequency of the area of interest were produced based on information derived from a geomorphological landslide inventory; the latter was generated by using very high resolution satellite stereo pairs along with information derived from other sources （Google Earth, aerial photographs and historical information）. Estimations of landslide susceptibility were determined by combining four statistical techniques： （i） logistic regression, （ii） quadratic discriminant analysis, （iii） linear discriminant analysis, and （iv） neuronal networks. A Digital Elevation Model （DEM） of lo m spatial resolution was used to extract the slope angle, aspect, curvature, elevation and relief. These factors, in addition to land cover, lithology anddistance to faults, were used as explanatory variables for the susceptibility models. Additionally, a Poisson model was used to estimate landslide temporal frequency, at the same time as landslide magnitude was obtained by using the relationship between landslide area and the velocity of movements. Then, due to the complexity of evaluating it, vulnerability of population was analysed by applying the Spatial Approach to Vulnerability Assessment （SAVE） model which considered levels of exposure, sensitivity and lack of resilience. Results were expressed on maps on which different spatial patterns of levels of landslide hazard and vulnerability were found for the inhabited areas. It is noteworthy that the lack of optimal methodologies to estimate and quantify vulnerability is more notorious than that of hazard assessments. Consequently, levels of uncertainty linked to landslide risk assessment remain a challenge to be addressed.展开更多
Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is ov...Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is over mature forest, and accounts for much proportion. Fire season in this area is winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire season lasts from October to next February,but to April in an individual arid year. Most of the fires in this area are surface fires, crown fire, can occur after long time drought. Ground fires do not occur in the region.展开更多
All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and ...All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and fuel-breaks trees were presented. The fire resistance mechanism includes 3 aspects, fire-resistanttree species, rational construction forest belts and environment. Tree crowns can resist fire forwarding.Forest belts can form the environment, which is not easy to fire, and also make fuels distributed discontinuous.The network of forest belts has large area of conifer forest segregated. The ideal fire resistant tree species hadbetter to embrace some characteristics, such as high fire resistance, rational planting and biological characteristics.展开更多
基金Projects KSTAS/MACRES/T/2/2004 supported by the Airborne Remote Sensing (MARS) Program of Malaysia, 4067113040671122 by the National Natural Science Foundation of China
文摘Based on the physical concept of heat energy of pre-ignition,a new fire susceptibility index (FSI) is used to estimate forest fire risk. This physical basis allows calculation of ignition probabilities and comparisons of fire risk across eco-regions. The computation of the index requires inputs of fuel temperature and fuel moisture content (FMC),both of which can be estimated using remote sensing data. While ASTER data for land surface temperatures (LST) was used as proxys for fuel temperatures,fuel moisture content is estimated by regression technique utilizing the ratio NDVI/LST of ASTER data. FSIs are computed in peninsular Malaysia for nine days before the fires of 2004 and 2005 and validated with fire occurrence data. Results show that the FSI increases as the day approaches the fire day. This trend can be observed clearly about four days before the day of fire. It suggests that FSI can be a good estimator of fire risk. The physical basis provides a more meaningful FSI,allows calculation of ignition probabilities and facilitates the development of a future class of fire risk models. FSI can be used to compare fire risk across different eco-regions and time periods. FSI retains the flexibility to be localized to a vegetation type or eco-regions for improved performance.
基金Project(41931294)supported by the National Natural Science Foundation of ChinaProjects(U1502232,U1033601)supported by the National Natural Science Foundation of China-Yunnan Joint Fund。
文摘To characterize and recognize the debris flow-related deposits,the physico-mechanical performance of four deposits from the Dongyuege(DYG),Shawa(SW),Jiangjia Gully(JJG),and Gengdi(GD)debris flows in southwest China is investigated through laboratory analyses and tests.The four debris-flow materials can all be remolded into coherent,homogeneous cylinders with high densification and strength–porosity of 25%-36%,mean pore-throat radius of 0.46-5.89μm,median pore-throat radius of 0.43-4.28μm,P-wave velocity of 800-1200 m/s,modulus of elasticity of 28-103 MPa,unconfined compressive strength(UCS)of 220-760 kPa,and cohesion of 65-281 kPa.Based on the comparison in slurryability and formability among debris-flow deposits,granular flow deposits,fluvial deposits,residual lateritic clay and loess,whether a sediment can be cast into competent cylinders for physico-mechanical tests can be regarded as a diagnostic evidence of old debris-flow deposits.The discrepancy in physico-mechanical properties among the four debris-flow deposits suggests that the combination of foregoing physico-mechanical parameters can characterize assembling characteristics of debris flow-related sediments including grain size distribution,mineralogy,and accidental detritus.Four deposited sediments above can be surprisingly classified as hard soil-soft rocks according to UCS,and the hard soil-soft rock behaviors can advance the further understanding of debris flows.
基金CONACyT for financial support for the research project 156242for providing a post-graduate scholarship
文摘In this paper, an attempt to analyse landslide hazard and vulnerability in the municipality of Pahuatlfin, Puebla, Mexico, is presented. In order to estimate landslide hazard, the susceptibility, magnitude （area-velocity ratio） and landslide frequency of the area of interest were produced based on information derived from a geomorphological landslide inventory; the latter was generated by using very high resolution satellite stereo pairs along with information derived from other sources （Google Earth, aerial photographs and historical information）. Estimations of landslide susceptibility were determined by combining four statistical techniques： （i） logistic regression, （ii） quadratic discriminant analysis, （iii） linear discriminant analysis, and （iv） neuronal networks. A Digital Elevation Model （DEM） of lo m spatial resolution was used to extract the slope angle, aspect, curvature, elevation and relief. These factors, in addition to land cover, lithology anddistance to faults, were used as explanatory variables for the susceptibility models. Additionally, a Poisson model was used to estimate landslide temporal frequency, at the same time as landslide magnitude was obtained by using the relationship between landslide area and the velocity of movements. Then, due to the complexity of evaluating it, vulnerability of population was analysed by applying the Spatial Approach to Vulnerability Assessment （SAVE） model which considered levels of exposure, sensitivity and lack of resilience. Results were expressed on maps on which different spatial patterns of levels of landslide hazard and vulnerability were found for the inhabited areas. It is noteworthy that the lack of optimal methodologies to estimate and quantify vulnerability is more notorious than that of hazard assessments. Consequently, levels of uncertainty linked to landslide risk assessment remain a challenge to be addressed.
基金NSFC Project (No. 30371170)National Technology R&D Program (No.2006BAD04B05)
文摘Southeast Tibet forest is in east subtropical zone. This region natural environment is unique, influenced by the southwest monsoon, so forest fires are very easy to occur in the dry season. Forest in this region is over mature forest, and accounts for much proportion. Fire season in this area is winter and spring. But in the special year, forest fires can also occur in the hot summer. Fire season lasts from October to next February,but to April in an individual arid year. Most of the fires in this area are surface fires, crown fire, can occur after long time drought. Ground fires do not occur in the region.
基金The research was supported by Research and Demonstration of Key techniques for natural forests protection program(2004) and Key Technologies R&D Programme (No. 2001BA510B09 )
文摘All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and fuel-breaks trees were presented. The fire resistance mechanism includes 3 aspects, fire-resistanttree species, rational construction forest belts and environment. Tree crowns can resist fire forwarding.Forest belts can form the environment, which is not easy to fire, and also make fuels distributed discontinuous.The network of forest belts has large area of conifer forest segregated. The ideal fire resistant tree species hadbetter to embrace some characteristics, such as high fire resistance, rational planting and biological characteristics.
